3D-HOPKINSON BAR : NEW EXPERIMENTS FOR DYNAMIC TESTING ON SOILS

抄録

The Split Hopkinson Pressure Bar method (S. H. P. B) provides a ready means for direct analysis of material dynamic response. Soil Specimens generally present poor mechanical properties, thus the classical experimental device has to be adapted. An original experimental arrangement "Three-Dimensional Split Hopkinson Pressure Bar" (3D-SHPB) is proposed. It allows measurement of the complete three-dimensional dynamic response of soils. Experiments are oedometric type tests (rigid confining cylinder) involving dynamic radial stress measurement. Pseudo Poisson's ratio is then determined and the influence of strain rate is shown. In addition, other types of confining systems are used : soft and semi-rigid confinement and low impedance tests are performed. Results on different loading paths are compared with others on sands and clays. Analysis at grain-size level gives further elements on the comminution process.